1. Technical Field to which the Invention Belongs
The present invention relates to a magnetic tape apparatus intended to attain a high speed operation in a fast feed mode and a rewind mode.
2. Related Art
As the prior art of the magnetic tape apparatus, there have been such examples as one disclosed in the Unexamined Japanese Patent Application Publication No. Hei 5-298783. One of the examples will be described referring to FIG. 9. Reference numeral 1 denotes a tape cassette, 2 denotes a pay-off reel table engaged with a pay-off reel of the tape cassette 1, 3 denotes a roll-up reel table engaged with a roll-up reel of the tape cassette 1, 4 denotes movable guide posts for winding a magnetic tape T drawn out from the tape cassette 1 around a head cylinder 5, 6 denotes an all width erase head, 7 denotes a voice erase head, 8 denotes a voice control head, 9 denotes stationary tape guide posts, 10 denotes a capstan motor for rotating a capstan 10a in a normal and a reverse directions, 11 denotes a pinch roller adapted to come into pressure contact with and move away from the capstan 10a, 12 denotes a tension lever for pressing a tension post 12a against the magnetic tape T, 13 denotes a mode switch lever which is placed on a chassis 14 so as to move to and fro in directions of arrow marks a and b.
A pivotal shaft 15 is provided on the chassis 14 between the pay-off reel table 2 and the roll-up reel table 3. A belt 18 is wound around a rotatable pulley 16 which is concentrically provided below the pivotal shaft 15 and a pulley 17 which is fixed to the aforesaid capstan 10a. An intermediate gear 19 is rotatably mounted around the pivotal shaft 15, and a clutch mechanism 20 for directly or indirectly connecting the intermediate gear 19 to the pulley 16 is provided. There is provided a rocking arm 21 adapted to rock to and fro in directions of arrow marks c and d around the pivotal shaft 15. An idler gear 22 pivotally fixed to an end of the rocking arm 21 is meshed with the intermediate gear 19. On both sides of the idler gear 22, there are arranged a roll-up gear 24 which is associated with teeth 3a of the roll-up reel table 3 by way of a gear 23, and teeth 2a formed around the pay-off reel table 2 in a mutually opposed manner.
The aforesaid clutch mechanism 20 includes a clutch shaft 20a rotatably supported on the chassis 14, a cam pin 20b which is provided projectingly at a middle part of the clutch shaft 20a and adapted to be engaged in a cam groove 13a of the mode switch lever 13, and an arm 20c provided projectingly on the clutch shaft 20a and adapted to be engaged with the intermediate gear 19.
In the above described structure, in a play back mode, the magnetic tape T is drawn out from the tape cassette 1 by means of the movable tape guide posts 4 and wound around the head cylinder 5. At the same time, the tension lever 12 is erected to push the tension post 12a against the magnetic tape T so that the magnetic tape T is placed under tension so as to be in a loading state. By driving the capstan motor 10 in the normal direction, the rocking arm 21 is rocked in the direction of the arrow mark d by way of the pulleys 16, 17 and the belt 18. In this manner, the idler gear 22 is allowed to mesh with the roll-up gear 24, and a rotary drive force of the pulley 16 is transmitted to the roll-up reel table 3 by way of a slip mechanism (not shown), the idler gear 22, and the gears 23, 24, and thus, the roll-up reel table 3 is rotated in a direction of an arrow mark e to roll up the magnetic tape T.
In order to switch the mode from the play back mode to a play back rewind mode, the capstan motor 10 is rotated in the reverse direction. This allows the rocking arm 21 to be rocked in the direction of the arrow mark c by way of the pulleys 16, 17 and the belt 18, and the idler gear 22 is meshed with the teeth 2a of the pay-off reel table 2. At the same time, the rotary drive force of the pulley 16 is transmitted to the pay-off reel table 2 by way of the slip mechanism, the intermediate gear 19 and the idler gear 22, and thus, the pay-off reel table 2 is rotated in a direction of an arrow mark f to roll up the magnetic tape T.
In a fast feed mode and a rewind mode, the mode switch lever 13 is shifted in the direction of the arrow mark b allowing an angled portion 25 of the cam groove 13a to be engaged with the cam pin 20b. This allows the intermediate gear 19 to be directly connected to the pulley 16 by means of the arm 20c of the clutch mechanism 20. In this manner, the rotary drive force of the pulley 16 is directly transmitted to the intermediate gear 19 so that the pay-off reel table 2 or the roll-up reel table 3 rolls up the magnetic tape T.
In the above described structure, in the fast feed mode and the rewind mode, the intermediate gear 19 is directly connected to the pulley 16 so as to directly rotate the pay-off reel table 2 or the roll-up reel table 3 by means of the capstan motor 10. However, since a speed increasing function is not provided, there has been a drawback that speed up of the rotation is limited, and a considerable time is required for the fast feed and the rewind of the magnetic tape T.
In view of such a conventional drawback as described above, it is an object of the invention to provide a magnetic tape apparatus in which fast feed and rewind of a magnetic tape can be conducted at high speed.
In order to attain the above described object, the invention as in aspect 1 is a magnetic tape apparatus comprising an intermediate gear meshed with an idler gear which can be releasably meshed with a pay-off reel table and a roll-up reel table, a drive gear rotatably driven by drive means, and a driven gear which can be releasably meshed with the drive gear by way of a slip mechanism, and constructed in such a manner that the intermediate gear is directly connected to the drive gear in a fast feed mode and a rewind mode and indirectly connected to the drive gear by way of the slip mechanism and the driven gear in a play back mode and a play back rewind mode, characterized in that the intermediate gear is connected to the drive gear by way of a speed increasing mechanism in the fast feed mode and the rewind mode.
According to the above described structure, the fast feed and the rewind of the magnetic tape can be finished in a short time, because the rotation speed of the pay-off reel table or the roll-up reel table can be increased by the speed increasing mechanism in the fast feed mode and the rewind mode.
The invention according to aspect 2 is, in the invention as in aspect 1, characterized in that the speed increasing mechanism includes a movable rotary body which is rotatably mounted around a support shaft and adapted to reciprocate along an axis of the support shaft, the movable rotary body being provided with a small diametered gear and a large diametered gear, and in the fast feed mode and the rewind mode, the large diametered gear is meshed with the intermediate gear while the small diametered gear is meshed with the drive gear.
According to the above described structure, in the fast feed mode and the rewind mode, the rotation speed of the pay-off reel table or the roll-up reel table can be increased due to a gear ratio between the large diametered gear and the small diametered gear. Moreover, because the structure of the speed increasing mechanism is simple, the magnetic tape apparatus is difficult to be broken and can be manufactured at a low cost.
The invention according to aspect 3 is, in the invention as in aspect 2, characterized in that the movable rotary body is integrally provided with a large high speed gear which is larger in diameter than the large diametered gear, and in the fast feed mode and the rewind mode, the large high speed gear is meshed with the intermediate gear while the small diametered gear is meshed with the drive gear.
According to the above described structure, in the fast feed mode and the rewind mode, by meshing the large high speed gear integrally formed with the movable rotary body with the intermediate gear, the rotation speed of the pay-off reel table or the roll-up reel table can be further increased.
The invention according to aspect 4 is, in the invention as in aspect 2 or 3, characterized in that the movable rotary body is provided with a large low speed gear, and in the play back mode and the play back rewind mode, the large diametered gear is meshed with the intermediate gear while the large low speed gear is meshed with the driven gear.
According to the above described structure, only by meshing the large low speed gear provided on the movable rotary body with the driven gear, the speed increasing mechanism can be switched also to the play back mode and the play back rewind mode and can be conveniently used.
The invention according to aspect 5 is, in the invention as in aspect 4, characterized in that the movable rotary body is provided with a neutral position in which the small diametered gear and the large low speed gear are not meshed with each other, and the movable rotary body is set at the neutral position in a stop mode.
According to the above described structure, by switching the mode from the fast feed mode and the rewind mode to the stop mode, the movable rotary body is set in the neutral position, thereby to instantaneously interrupt the rotary drive force of the drive gear. Therefore, the magnetic tape can be prevented from being excessively rolled up around the pay-off reel table or the roll-up reel table.